Real-time arc control in electrosurgical generators

Abstract

An electrosurgical generator is disclosed. The generator includes a radio frequency output stage configured to generate a radio frequency waveform and a sensor circuit configured to measure a property of the radio frequency waveform during a predetermined sampling period to determine whether an arc event has occurred. The generator also includes a controller configured to determine a total charge and/or total energy deposited by the radio frequency waveform during the predetermined sampling period associated with the arc event. The controller is further configured to adjust the output of the electrosurgical generator based on at least one parameter to limit arcing.

What is claimed is: 
     
       1. An electrosurgical generator comprising:
 a radio frequency output stage configured to generate at least one radio frequency waveform having a voltage waveform and a current waveform; 
 a sensor circuit configured to determine at least one property of each of the voltage waveform and the current waveform during a predetermined sampling period; 
 a shunt capacitor disposed between active and return terminals of the electrosurgical generator; 
 a controller configured to compare the at least one property of each of the voltage waveform and the current waveform to determine at least one deviation between the at least one property of each of the voltage waveform and the current waveform indicative of an arc event, the controller further configured to determine at least one of total charge, total energy and duration of the arc event based on the at least one deviation, wherein the controller includes a total energy calculator module configured to temporally integrate a product of total charge deposited by the at least one radio frequency waveform and voltage across the shunt capacitor to determine the total energy deposited by the at least one radio frequency waveform during the predetermined sampling period. 
 
     
     
       2. An electrosurgical generator according to  claim 1 , wherein the controller is further configured to adjust the output of the electrosurgical generator based on the at least one deviation. 
     
     
       3. An electrosurgical generator according to  claim 2 , wherein the controller includes a total charge calculator module configured to temporally integrate the voltage waveform to determine the total charge deposited by the at least one radio frequency waveform during the predetermined sampling period. 
     
     
       4. An electrosurgical generator according to  claim 2 , wherein the total energy calculator is further module configured to temporally integrate total power deposited by the at least one radio frequency waveform to determine the total energy deposited by the at least one radio frequency waveform during the predetermined sampling period. 
     
     
       5. An electrosurgical generator according to  claim 1 , further comprising:
 a resistor and an inductor coupled in series with the active terminal. 
 
     
     
       6. An electrosurgical generator according to  claim 5 , wherein the controller is configured to determine a desired amount of energy to be deposited into tissue per arc event based on a formula E=CV 2 /2+LI 2 /2, wherein E is the desired energy, C is capacitance of the shunt capacitor, L is inductance of a series inductor, I is current and V is voltage measured across the shunt capacitor. 
     
     
       7. A method for operating an electrosurgical generator, comprising the steps of:
 generating at least one radio frequency waveform having a voltage waveform and a current waveform; 
 determining at least one property of each of the voltage waveform and the current waveform during a predetermined sampling period; 
 measuring amplitude of the voltage waveform across a series resistor of the electrosurgical generator during the sampling period; 
 comparing the at least one property of each of the voltage waveform and the current waveform to determine at least one deviation between the at least one property of each of the voltage waveform and the current waveform indicative of an arc event; 
 determining at least one of total charge, total energy and duration of the arc event based on the at least one deviation; 
 measuring voltage across a shunt capacitor disposed between active and return terminals of the electrosurgical generator during the sampling period; and 
 temporally integrating a product of the total charge and the voltage across the shunt capacitor to determine total energy deposited into tissue by the at least one radio frequency waveform during the sampling period. 
 
     
     
       8. A method according to  claim 7 , further comprising the steps of:
 temporally integrating voltage across the series resistor to determine total charge deposited into tissue by the at least one radio frequency waveform during the sampling period; and 
 temporally integrating power of the at least one radio frequency waveform during the sampling period to determine total energy deposited into tissue by the at least one radio frequency waveform during the sampling period. 
 
     
     
       9. A method according to  claim 7 , further comprising the steps of:
 calculating a desired maximum amount of energy to be deposited into tissue per arc event to limit the arc event; and 
 adjusting output of the electrosurgical generator based on the desired maximum amount of energy to be deposited into tissue per arc event. 
 
     
     
       10. A method according to  claim 9 , wherein the step of calculating the desired maximum amount of energy is based on a formula E=CV 2 /2+LI 2 /2, wherein E is the desired energy, C is capacitance of the shunt capacitor, L is inductance of a series inductor, I is current and V is voltage measured across the shunt capacitor.